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    <script>
        // 翻转数组
        // function reverse(arr){
        //     var newArr = [];
        //     for(var i =arr.length-1;i>=0;i--){
        //         newArr[newArr.length] = arr[i];
        //     }
        //     return newArr;
        // }
        // console.log(reverse([1,2,3]));
        // console.log(reverse(1,2,3));

        function reverse(arr){
            if(arr instanceof Array) {
            for(var i =arr.length-1;i>=0;i--){
                newArr[newArr.length] = arr[i];
            }
            return newArr;
        }else {
            return'error 这个参数要求必须是数组格式 [1,2,3]'
        }
    }
        console.log(reverse([1,2,3]));
        console.log(reverse(1,2,3));
        //检测是否为数组
        //(1)instanceof 运算符 可以用来检测是否为数组
        var arr = [];
        var obj = {};
        console.log(arr instanceof Array);
        console.log(obj instanceof Array);
        //(2)Array.isArray(参数);H5新增的方法  ie9以上版本支持
        console.log(Array.isArray(arr));
        console.log(Array.isArray(obj));
    </script>
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